How to Make, Repair and Upgrade Laptop and Notebook Power Supplies, AC/DC Adapters and Power Jacks

How to make, repair and upgrade power supplies for laptops and notebooks.
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Inside this laptop power from the AC adapter goes to the motherboard through the power board. When the power board goes bad, the laptop stops working at all and appears to be dead. In order to get access and replace the power board the entire laptop has to be taken apart.

These picture gallery illustrates how to replace a fried charger chip (ISL6251) on the laptop motherboard. The manufacturer did not bother protecting against idiots who connect power adapters with the wrong polarity. Fortunately it is possible to fix this issue by replacing the chip, a diode, two FETs, one inductor and one resistor.

It seems that many NC100 owners plug in a third-party power supply instead of running the machine on batteries. Unfortunately, the standard-looking power connector has its polarity reversed from what is usual: The outer side of the connector is +, the inside is -. Alas, a fuse in the NC100 blows up when you get the polarity wrong. This results in a dead machine. Null modem cable trouble: The normal way to communicate with the NC100, lacking a disk drive, is to use a null modem cable, but standard cables don't work here is the fix: solder a wire between RTS and CTS on the NC connector - short pins 7 and 8.

The DC plug of Apple Power Adapters: have you ever wondered about how the illumination in the DC plug of the DC adapter of your PowerBook or iBook works? Occasionally the cap broke once when I was trying to unplug the connector, so it revealed its internals.

This notebook sometimes had adapter issues, the cord frays inside because of the stress from wrapping it up around the adapters "ears". The solution: Tear it apart and replace the broken section! The tools to use are heatshrink, chisel, hammer, razor blade (for cutting and stripping wires), and voltmeter. Additional items are tape (electrical, duct, vinyl) and fuel hose.

The power jack started failing intermittently. The laptop started switching from AC to battery power on its own. In order to switch it back to the AC power you have to fiddle with the adapter plug and find the right position. If the laptop failes exactly the same way with another adapter, the conclusion is that the DC power jack is not making good contact with the motherboard and has to be repaired. Inside this laptop the DC power jack is soldered to the motherboard. If the jack is broken, you'll have to unsolder it and replace with a new jack.

A quick fix to run a laptop from a DC-DC convertor. The only trouble is, the laptop has an odd square plug and the convertor only has round plugs. An in-line adaptor made from a pen barrel solves the problem.

In a this laptop the power jack is soldered to the motherboard. If the laptop looses power intermittently when you wiggle the power plug, most likely the power jack is damaged and has to be repaired. In order to repair the power jack you will have to remove the motherboard.

This laptop stopped charging the battery even though the AC adapter worked properly and provided correct voltage. The adapter was tested with a voltmeter. It charged the battery but only intermittently, when the AC adapter was pushed in firmly. In order to charge the battery the AC adapter plug inside the power socket on the back of the laptop had to be adjusted and resoldered.

When the LED light on the DC jack starts flickering when adapter plug is moved, you can test the laptop with another known good AC adapter, but if this approach does not fix the problem you can assume this is a DC jack related failure and you need to replace it.

Healing a 'crazy cursor' bug which causes the pen/cursor to move to and click at the top right hand corner of the screen (in Portrait mode) or the button right hand corner of the screen (in Landscape mode). This can cause randomly close windows or open up the Date and Time dialog box. Very annoying! The real hardware reason for this problem is caused by AC leakage from the power supply (which should be outputting only DC and very low amounts of AC). 80VAC zooming around trying to earth the device probably generates quite a bit of EM interference which screws around with the tablet digitizer. You can permanently fix the problem by adding additional electro-magnetic shielding to your Tablet PC. All you need are a screwdriver and some aluminium foil.

In order to access the cooling fan you have to remove the bottom cover. This guide also explains how to access the laptop memory, DVD drive, hard drive, wireless card, audio board, SC card reader, CMOS battery and power jack.